A typology of defectiveness

An important design feature of language is the use of productive patterns. We have 'enjoy' ~ 'enjoyed', 'agree' ~ 'agreed', and many others. On the basis of this productive pattern, if we meet a new verb 'transduce' we know that there will be the form 'transduced'. Even if the pattern is not fully regular, there will be a form available, as in 'understand' ~ 'understood'. Surprisingly, this principle is sometimes violated, a phenomenon known as defectiveness, which means there a gap in a word's set of forms. The missing singular form of English 'scissors' is one example, and more striking instances can be found in languages with more complex systems of inflection (for example, Russian nouns that lack a genitive plural, or verbs which lack a first person singular form).
Although such gaps have been known to us since the days of Classical grammarians, they remain poorly understood. It is generally assumed that the rules of language encode how things are to be done, and that speakers extrapolate these rules to all the words they encounter. This is how language is structured, and this how language is learned, or so we think. Defectiveness contradicts these assumptions, because it seems to require that speakers know that for certain words, not only should one not employ the expected rule, one should not employ any rule at all. This is a serious problem, since it is probably safe to say that all reigning models of grammar were designed as if defectiveness did not exist, and would lose a considerable amount of their elegance if it were properly factored in. However, at present, we cannot go very far in addressing the issue, since we have only fragments of data from an odd assortment of languages, each with its own peculiarities and each being given its own analysis. But the problem is too challenging to yield to this piecemeal approach. In order to make any substantial assessment of what defectiveness implies for grammatical theory, we need a much deeper and more extensive understanding of its typological range. We pose the following research questions:

1. How prevalent is defectiveness in the world's languages?
2. What grammatical features can be affected?
3. What kinds of paradigms are subject to gaps?
4. How does defectiveness arise historically? What happens to it over the course of time?

These questions will be addressed by the construction of larges-scale cross-linguistic and typological databases (which will be made publicly available over the internet as part of the Surrey Morphological Databases project), and historical case studies of selected phenomena. Further, we will raise awareness of the importance of defectiveness for linguistic theory by holding a dissemination conference. The results of these investigations will be of interest to all linguists interested in the architecture of inflection, to typologists, to psycholinguists and to researchers in language acquisition.